Fuel Ethanol’s Role in the Fight Against Climate Change

In December 2015, 196 nations made a pact known as the World Climate Agreement, with a goal of, “holding the increase in global average temperature to well below 2° Celsius above pre-industrial levels.” A key factor in whether we as a global community are able to meet that goal will be our ability to reduce CO2 and other GHG emissions.

The true cost of fossil fuels

Fossil fuels—coal, oil and natural gas—serve as the world’s primary source of energy. They make up approximately 80% of total energy consumption worldwide, and replacing them with cleaner energy sources is a difficult endeavor to say the least. However, continuing the use of fossil fuels will push us well beyond 2° above pre-industrial levels, which will cause devastating shifts in climates around the world, decimating coastal cities and island nations and causing irreparable harm to the planet’s delicate ecosystems. The U.S. alone emitted 6.87 billion metric tons of CO2 in 2014. If those environmental costs are factored into the price of fossil fuels, they suddenly become much more expensive.

Yet consumers most readily associate the cost of fossil fuels with the prices they pay at the pump; nearly 26% of the U.S.’s 6.87 billion metric tons of CO2 came from the transportation sector. Currently, fossil fuels account for 95% of U.S. transportation sector consumption. The lack of consideration for environmental costs is particularly alarming given that we’re already more than halfway to our 2° limit under the World Climate Agreement, and the fact that completely renewable energy is still years, if not decades, away.

One tool currently at our disposal, however, is bioethanol. Nowadays, ethanol is already replacing gasoline as an additive to the existing fuel mix. But starch-based ethanol additionally produces a low-cost feed ingredient rich in energy, protein, and phosphorus as a co-product. Cellulosic ethanol, which is often co-produced with bioelectricity, biogas and biofertilizers, can be produced alongside starch-based ethanol.

Because of these applications, ethanol is already displacing a lot of gasoline today. In the years to come, though, ethanol could play an even bigger role, working in concert with other technologies to drastically reduce GHG emissions. Those technologies, such as 100% ethanol-fueled vehicles and bioenergy with carbon capture and storage, are showing promising perspectives. But we don’t have to just sit back and wait. We can still move the needle today by making better use of available ethanol technologies.

Cutting emissions with starch- and sugar-based ethanol

In the history of transportation fuels, the mass production—and, to an extent, use—of starch- and sugar-based ethanol is quite recent, but these fuels indicate there is hope for a more harmonious future between sustainable energy and the transportation industry.

Corn serves as the primary source of the world’s starch-based ethanol, and it’s no surprise that most of the corn comes from the farmlands of the U.S. Today, the GHG emissions from U.S. corn ethanol are roughly 55.7 kg CO2e/MMBtu or 53 g CO2e/MJ. This includes emissions from so-called indirect land use change (ILUC). Hence, the emission assessment is based on a so-called marginal or consequential approach. Taking a similar approach to gasoline production leads to emissions of 115 g CO2e/MJ. This means that the relative GHG saving in a marginal/consequential perspective for average U.S. ethanol is around 54%.

Brazil, the world’s second largest ethanol producer, derives the fuel from sugarcane. Emissions from sugarcane ethanol are, on average, 51% lower than average gasoline (~60% compared to marginal gasoline). Under the U.S.’s Renewable Fuels Standard (RFS), the Environmental Protection Agency (EPA) considers sugarcane ethanol an Advanced Renewable Fuel because it cuts CO2 emissions by more than 50% compared to average gasoline.

Creating fuel ethanol from plant matter

Producers around the world are also working on other forms of renewable fuel that will provide even higher GHG savings. Also known as cellulosic ethanol, these fuels take plant matter from cellulose and hemicellulose to make a sustainable fuel.

Unlike most starch- and sugar-based ethanol, biomass used to create cellulosic ethanol can be derived from residues and waste. Examples include municipal waste, by-products from agriculture, forestry, and processing industries as well as a number of different grasses. Using these feedstocks, the fuel produced can help to efficiently meet the EPA’s emission reduction goals.

And, innovation in the renewable fuel space is constantly progressing. DONG Energy announced the development of the world’s first full-scale bio plant that will convert unsorted household waste into biogas—a process made possible by enzymes that Novozymes will provide. Biorefineries—facilities that produce fuels, power, heat and value-added chemicals from biomass—are even producing biofertilizers from the same products that are yielding the fuel. Additionally, the bioelectricity from these facilities can help to balance power fluctuations due to wind and solar energy sources.

The future of bioenergy is exciting, to be sure. But our planet’s climate won’t wait indefinitely while we work to find the perfect energy source.